copper, sulfur, helium and mercury. Explain which you think are metals.

Copper and mercury are metals.

Here's why:

1. Copper (Cu): Copper is a chemical element with the symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. It is one of the few metals that can occur in nature in a directly usable metallic form. This led to very early human use in several regions, from c. 8000 BC.

2. Sulfur (S): Sulfur is not a metal; it is a nonmetal. It is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent, and nonmetallic. Sulfur, in its native form, is a bright yellow crystalline solid.

3. Helium (He): Helium is not a metal; it is a noble gas. It is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table.

4. Mercury (Hg): Mercury is a metal. It is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum. A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure.